Furnace



N Aug. 29, 1939. c. H. LENGYEL FURNACE Filed March 1, 1939 Patented Aug.29, 1939 UNITED" STATES PATENT OFFICE FURNACE Carl H. Lengyel, Kenmore,N. Y.

Application March 1, 1939, Serial No. 259,186

9 Claims.

This invention relates to furnaces and has particular reference toapparatus for affording a more efficient conversion of the chemicalenergy of fuel to heat by combustion.

The present invention may be said to have as its fundamental concept thesubstantial preheating of air before its deliverance to the point wherethe principal combustion of the furnace takes place, taken together witha more efl'icient in transfer of the heat of combustion for general usein heating. Procedure in accordance with the teaching of my invention isfound to result in a far more complete combustion of the fuel and in amore rapid transfer of the heat of coml bustion to the air passingthrough the zone of combustion.

While multiple-stage heating may not, as a broad concept, be novel tothe present invention, the manner in which the plural effect heating is20 accomplished is not believed to be known in the prior art. Previousexamples of step or multiple effect heating have depended upon theprovision of multiple heating chambers and sometimes even on multiplefuel burners. In the present 25 invention the effect of step-heating isachieved without such complication of the apparatus and by utilizing thehigh heat conductivity of iron or a like material in a novel manner.

In the present invention the fire pot or com- 30 bustion chamber is soarranged that all of the incoming atmosphere is received through anannular conduit which has communication with the lower portion of thecombustion chamber.

The actual combustion is preferably arranged to.

35 take place in the vicinity of the upper rim of such annular conduitwhere it communicates with 'the interior of the fire pot. This may beaccomplished by disposing a number of fluid fuel burning jets directlyabove or immediately out- 40 side of the upper portion of the annularconduit and one convenient mode of arranging the apparatus of myinvention is to so form the upper part of the annular conduit that ititself constitutes a burner comprising a circle of fuel burn- 45 ingjets leading from the upper face of the annular ring.

In proceeding according to my invention a special heat conducting andradiating element is provided for cooperation with the annular ,0conduit, the fuel burner itself, and the walls of the combustionchamber. This element may be of a variety of forms but in one highlysatisfactory embodiment of the apparatus of my invention a casing isprovided which is similar in 55 conformation and nearly as large as thelower portion of the interior of the normal combustion chamber of thefurnace. This casing is formed of a material which has a relatively highheat conductivity, cast iron being well suited to the requirementspresented, and the casing has a 5- lower terminal portion which ineffect extends downwardly into the annular conduit, having preferably adownwardly convex contour for achieving this result.

An exterior circular zone on the casing is. disl0 posed relatively closeto the fuel burners whereby combustion takes place substantially againstsuch zone and from this point upward the casing is spaced inwardly ofthe interior wall of the fire pot a relatively short distance wherebyheat may readily be radiated from the diverging walls of the casing tothe closely adjacent walls of the fire pot for transmission therethroughand exchange with a fluid, usually one that is being circulated aroundthe outside of the fire pot.

The casing walls are of moderate thickness and the hollow interior ofthe casing is preferably filled with material having good heatinsulating qualities, rock wool having been found highly satisfactoryfor the purposes of the present invention. It will be seen from thisthat heat imparted to the casing in the zone of combustion will beconducted rapidly along the wall of the casing and experiment shows thatin an installation comparable in size and proportion to a usual domesticconversion burner installation the casing wall becomes cherry red withina relatively short period of time and over a considerable area, sucharea extending down to the very bottom of the casing where it isdisposed within the annular conduit.

As a result of this heating of the casing walls to a relatively hightemperature the incoming draft air, which enters upwardly through theannular conduit must of necessity come into close proximity to thehighly heated surface of the lower portion of the casing wall and infact the major portion of such draft will, by virtue of the arrangementof the parts of the apparatus, traverse a large portion' of the part ofthe casing wall which is disposed below the actual burners.

The result of the foregoing operation is that the draft air, upon itsarrival at the burners, has already been brought to a relatively hightemperature, as compared with the temperature of draft air in prior artdevices of this type, and the gas, or carbureted fuel if such be used.is burning in an atmosphere which-is very much closer to its naturalcombustion temperature with a consequently more thorough, eflicient, andcomplete liberation, in the form of heat, of the chemical energycontained in the fuel.

A further improvement in efficiency is effected by the arrangement ofthe walls of the casing with respect to the walls of the fire pot orcombustion chamber as these elements extend upwardly above the burners.The proximity of the casing. wall to the interior surface of thecombustion chamber results in radiation of heat to the latter in amanner which will appear from a further consideration of the details ofconstruction of the casing itself.

For disclosing a complete embodiment of my invention I have illustratedthe principles thereof in connection with a furnace of a type widelyemployed domestically and having a conversion burner associatedtherewith. It is to be understood, however, that this embodiment ischosen merely by way of example and that such modifications as aredictated by varying conditions may be made without departing from thespirit or scope of the present invention as defined in the appendedclaims.

In the drawing:

Fig. 1 is a general side elevation of a. furnace with portions brokenaway to show the fire pot and combustion chamber thereof, which latterparts are illustrated in vertical cross section;

Fig. 2 is a fragmentary perspective view of one form of combined fuelburner and draft confining means in transverse cross section; and

Fig. 3 is a partial plan view of the combined burner and conduit ring ofFig. 2 with a portion of an inner casing member of my invention inhorizontal cross section taken at about the upper level of the burnerring.

In the drawing like characters of reference denote like parts and thenumeral II] designates a furnace casing having thereina fire pot andcombustion chamber I I which may be of conventional sectionalconstruction. Suitable means are provided for circulating air throughthe furnace I and about and in contact with the outside of thecombustion chamber I I to heat the air for transmission to other points,usually to the room of a building to be heated. The novelty of thepresent invention, as it affects the construction of a furnace of thetype being used as an example, is confined to the interior of thecombustion chamber and the draft passage thereto and the remainingconstruction of the furnace proper may therefore be along conventionallines and will not be discussed in detail.

It will be noted that the combined fire pot and combustion chamber shownin the drawing has a lower annular portion which converges downwardlyand an upper annular portion which converges upwardly, so that thecombined device II has an enlarged medial portion and converging taperedportions extending both upwardly and downwardly therefrom. Where thefurnace has originally been designed for use with solid fuel an ash pitwill be disposed beneath the fire pot and combustion chamber II as at I2and the ash pit also serves to convey draft air to the combustionchamber. In any event some source of air for supporting combustion willbe provided at the lower side of the casing which houses the burner orother primary heat source.

In one means for accomplishing the results aimed at in my invention Iprovide an annular ring I3 which serves as an upward extension of theopening connecting the ash pit I2 or other draft source with the firepot or combustion chamber II. The burning means are to be arranged inintimate association with the upper terminus of the ring I3 and forconvenience of manufacture the upper end of the ring I3 may itself beformed to constitute a ring of jets for the combustion of fluid fuel.

As appears from a consideration of Figs. 1 and 2 of the drawing, thering I3 has a circular conduit I4 formed at its upper inner side and atone point the conduit I4 has a downward extension I5 for communicationwith a source of fluid fuel. Merely by way of example I have shown theapparatus of my invention as arranged to utilize fuel gas but liquidfuel in the form of oil may be employed by making suitable modificationsin the equipment and its arrangement.

A plurality of burners II are arranged about the ring I3 and theseburners may constitute tubes which extend vertically completely throughthe conduit and are open at both their upper and lower ends. Suitableopenings I8 are formed in the tubes at points located within theinterior of the conduit I4 for the purpose of admitting fuel gas to theindividual tubes. The upper ends of the tubes constitute gas jets andthe openings at the lower ends of the tubes serve to admit air to thetubes for mixture with the gas in the manner which is usual in burnersoperating according to the Bunsen principle.

Fuel gas is piped to the ring I3 by any suitable piping 20 and entersthe conduit I4 by way of the downward extension I5 thereof. Whileautomatic control of the operation of the furnace is not necessary tooperation of my invention, I have shown schematically a casing 2i whichis interposed in the piping 20 and. contains a thermostaticallycontrolled valve. The operation of such valve is also usually arrangedto control admission of draft air to the furnace so that the furnacewill not become cooled by convection currents therethrough after theburners have been turned off by operation of the automatic controlvalve. Such means are indicated in Fig. 1 where a casing 23 whichcommunicates with the combustion chamber through the ash pit I2 isprovided with a valve 24 which operates with the gas control valvethrough a mechanical connection 25.

A pilot light 28 may be provided and in the i1- lustrated instance thepilot light is fed through a conduit 29 which communicates with thepiping 20 beyond the automatic valve mechanism so that it is in constantcommunication with the gas supply unless it is manually turned off bymeans of a valve 30. To supply oxygen for operation of the pilot 28 asmall vent 3| is provided in the wall of the casing 23. Of course manyforms of protective devices for both the pilot light and the feeding offuel to the burners may be employed in conjunction with the apparatus ofmy invention without affecting the novel mode ofoperation proposedherein.

I shall now describe an element which is disposed within the combustionchamber and is of such conformation and is so positioned as to affectthe fluid current through the furnace both prior to and after itspassage past the burners. The shape and arrangement of the elementreferred to here will vary with variations in the arrangement of thecombustion chamber and the burners of furnaces to which my invention isto be applied but in furnaces which have the conventional fire pot andcombustion chamber and are of the type illustrated in the drawingherein, the element may take the form of a substantially ellipsoidalcasing member.

In the specific example of the drawing I have U6. SYQVES & FURNACES,

shown complementary upper and lower casing portions 33 and 34respectively which comprise relatively thin cast iron walls and form aclosed ellipsoidal casing and for more flexible and efficient operationI preferably fill the interior space thereof with a good insulatingmaterial which may be rock wool, or the like, and is designated 35 inthe drawing. The relatively thin heat conducting casing wall and thefact that the large space inside the casing is not heat absorbentminimizes the amount of heat that might under other conditions pass offat the top of the casing into the flue and be wasted. The casing 33, 34may be supported in its illustrated position by projections 36 formedintegrally with the burner ring l4 or in any other convenient manner andits position is such that a relatively narrow annular passage isprovided between the upper inside edge of the ring 14 and the adjacentsurface of the lower casing portion 34.

It will be noted that with the casing in this position the lower convexor 'ovoid portion of the casing portion 34 projects downwardly into thespace enclosed within the ring l3 and in such manner as to present anupwardly diverging more or less conical wall leading to the region ofthe burners H. Progressing upwardly beyond the burners I1 the wall ofthe casing approaches a position of relatively close proximity to theinner Wall of the fire pot or combustion chamber I l and continues insuch condition of proximity to a point substantially above the largestlateral dimension of the combustion chamber.

It is particularly to be noted that the ring l3 fits closely over theopening between the combustion chamber H and the lower draft chamber orash pit l2 and that as a consequence no air is permitted to enter thecombustion chamber ll save through the central opening in the ring l3.When the furnace is put into operation by supplying gas to the burnersl1, the burners heat the casing 33, 34 to a red heat and owing to thehigh heat conductivity of the casing, the heat is conducted over asubstantial area of the casing both upwardly and downwardly of theburners II. In fact, the high degree of heat imparted to the casing 33,34 in this manner carries down along the converging lower portion of thecasing element 34 to its very bottom.

It will be seen from the foregoing that air coming to the combustionchamber from the draft passage l2 comes into contact with this highlyheated lower portion of the casing element 34 before it arrives at theburners H, as shown by the arrows in Fig. 1, and is so brought to arelatively high temperature before reaching the vicinity of the burners.With the surrounding atmosphere in such a heated state the gas issuingfrom the burners l l is very much closer to its natural ignitiontemperature and a much more thorough and efficient combustion thereoftakes place than in prior art practices.

The burners are so arranged that they play directly against the adjacentcasing wall and the casing wall above the burners I1 is so arranged thatwhatever heat is not conducted to the bottom of the casing forpreheating draft air is radiated from the casing wall to the closelyadjacent wall of the combustion chamber. While the contour of the uppercasing portion 33 has been illustrated as forming a continuation of therelatively narrow annular space between the casing and the inner surfaceof the wall of the combustion chamber l I, this is not necessary tosatisfactory operation. When the walls of the combustion chamber llbegin to converge upwardly, the natural convection current of the heatedair is upward against the wall of the chamber, whether or not theinfluence of the upper casing portion 33 is present.

Access may be had to the interior of the combustion chamber H by meansof the door 38 and in order that the pilot light 28 may be renderedaccessible for lighting and inspection, the casing 33, 34 is shownflattened in the vicinity of the door 38 as at 39.

The efficiency of heat transfer in the furnace of the present inventionis evidenced in actual installations by the coolness of the stackleading from the furnace and the all-around efficiency of combustion andheat transfer is proved by the relative economy of operation as comparedwith comparable furnaces of other types using the same fuel.

I claim:

1. In a furnace having a combustion chamber and an opening at the bottomthereof, a conduit leading upwardly from a source of draft tocommunicate with said opening, a plurality of bumers spaced about andclosely adjacent the upper end of said conduit, and a pre-heatingelement comprising a casing of heat conducting material having adownwardly convex portion disposed over and in close proximity to saidburners whereby its more central portions are disposed below saidburners and substantially within said conduit whereby to be contacted byincoming draft 2. In a furnace having a combustion chamber and anopening at the bottom thereof, a conduit leading upwardly from a sourceof draft to communicate with said opening, a plurality of burners spacedabout and closely adjacent the upper end of said conduit, and a body ofheat insulating material having a casing of heat conducting material,said casing having a downwardly convex portion disposed with portionsthereof in close proximity to said burners and with its more centralportions disposed substantially within said conduit.

3. In a furnace having a combustion chamber and an opening at the bottomthereof for communication with a source of draft, an annular conduitleading upwardly from said opening, a plurality of burners arrangedconcentrically with respect to said conduit and adjacent the upper endthereof, and a body of heat insulating material having a casing of heatconducting material, said casing having a downwardly convex portiondisposed in close proximity to said burners and substantially concentrictherewith whereby its more central portions project downwardly into saidconduit element.

4. In a furnace having a combustion chamber and an opening at the bottomthereof, a conduit leading upwardly from a source of draft tocommunicate with said opening, a plurality of burners spaced about andclosely adjacent the upper end of said conduit, and means for divertingair for flow through said conduit and said combustion chamber in apredetermined manner, said means being disposed in said combustionchamber and comprising a casing shaped similarly to the combustionchamber but smaller than said combustion chamber whereby to formtherewith a relatively narrow annular air passage upwardly from saidburners, the lower portion of said casing comprising a downwardly convexportion disposed in close proximity to said burners and with its morecentral portions disposed substantially within said conduit.

in ROW 5. In a furnace having a combustion chamber and an opening at thebottom thereof, a conduit; leading upwardly from a source of draft tocommunicate with said opening, a plurality of burners spaced about andclosely adjacent the upper end of said conduit, and means for divertingair for flow through said conduit and said combustion chamber in apredetermined manner, said means comprising a casing disposed in saidcombustion chamber and shaped similarly to the combustion chamber butsmaller than said combustion chamber to form therewith a relativelynarrow annular air passage upwardly from said burners, the lower portionof said casing comprising a downwardly converging portion disposed inclose proximity to said burners and projecting downwardly therefrom intosaid conduit whereby air passing upwardly through said conduit contactsthe surface of said lower casing portion and is diverted outwardly andupwardly therealong to be heated thereby before it reaches said burners.

6. In a furnace having a combustion chamber and an opening at the bottomthereof, a conduit leading upwardly from a source of draft tocommunicate with said opening, a plurailty of burners spaced about andclosely adjacent the upper end of said conduit, and pre-heating meanscomprising an element of heat conducting material having downwardlyconverging walls disposed in close proximity to said burners andprojecting downwardly therefrom into said conduit whereby air passingupwardly through said conduit contacts the surface of said lower casingportion and is diverted outwardly and upwardly therealong to be heatedthereby before it reaches said burners.

7. In a furnace having a combustion chamber and an opening at the bottomthereof, a conduit in communication with said opening and leadingupwardly from a source of draft, a plurality of burners spaced about andclosely adjacent the upper end of said conduit, and means in saidcombustion chamber for diverting air for flow through said conduit andsaid combustion chamber in a predetermined manner, said means comprisinga body of heat insulating material having a relatively thin heatconducting casing,

said casing being shaped similarly to the combustion chamber but smallerthan said combustion chamber whereby to form therewith a rela-.

tively narrow annular air passage extending upwardly from said burners,the lower portion of said casing comprising a downwardly convex portiondisposed in close proximity to said burners and with its more centralportions disposed below said burners and substantially within saidconduit.

8. In a furnace having a combustion chamber and an opening at the bottomthereof, a conduit in communication with said opening and leadingupwardly from a source of draft, a plurality of burners spaced about andclosely adjacent the upper end of said conduit, and means in saidcombustion chamber for diverting air for flow through said conduit andsaid combustion chamber in a predetermined manner, said means comprisinga body of heat insulating material having a relatively thin heatconducting casing, said casing being shaped similarly to the combustionchamber but smaller than said combustion chamber whereby to formtherewith a relatively narrow annular air passage extending upwardlyfrom said burners, the lower portion of said casing comprising adownwardly converging portion disposed in close proximity to saidburners and projecting downwardly therefrom into said conduit wherebyair passing upwardly through said conduit contacts the surface of saidlower casing portion and is diverted outwardly and upwardly therealongto be heated thereby before it reaches said burners.

9. In a furnace havinga combustion chamber and an opening at the bottomthereof, a conduit leading upwardly from a source of draft tocommunicate with said opening, a burner ring disposed about and closelyadjacent the upper end of said conduit, and a pre-heating elementcomprising a casing of heat conducting material having a downwardlyconvex portion disposed over and in close proximity to said burner ringwhereby its more central portions are disposed below said burner ringand substantially within said conduit whereby to be contacted byincoming draft air.

CARL H. LENGYEL.

